\Mor"dant\, n. [F., originally, biting.]
1. Any corroding substance used in etching.
2. (Dyeing & Calico Printing) Any substance, as alum or
copperas, which, having a twofold attraction for organic
fibers and coloring matter, serves as a bond of union, and
thus gives fixity to, or bites in, the dyes.
3. (Gilding) Any sticky matter by which the gold leaf is made
to adhere.